Evaluation of the three-dimensional position of the femoral head center after arthroscopic surgery for femoroacetabular impingement

Background The femoral head center may be affected by arthroscopic surgery for cam-type femoroacetabular impingement (FAI) due to cam resection or joint capsule management. This study aimed to evaluate femoral head center before and after arthroscopic surgery using computer analysis based on patient-specific pre- and postoperative three-dimensional (3D) computed tomography (CT). Methods CT scans of 22 patients with FAI (14 cam type and 8 mixed type) who underwent arthroscopic surgery were retrospectively evaluated. The distances between the femoral head center and the acetabular center were evaluated using preoperative and postoperative CT scans, and positional changes of the femoral head center were compared. We compared the femoral head positions of pre-and post-surgery. Net changes in the femoral head center were evaluated in the mediolateral and anteroposterior directions. Results There was no significant change in the femoral head center in the mediolateral (change − 0.08 mm, standard deviation 1.49 mm) and anteroposterior directions (change 0.22 mm, standard deviation 1.12 mm). There was no significant difference in these values compared with the non-operated contralateral side. Conclusion In this exploratory cohort, no statistically significant pre- to postoperative difference in the resting femoral head position was detected on supine CT after arthroscopic cam resection with capsular repair. These findings should not be interpreted as evidence of preserved dynamic hip stability. Further research incorporating dynamic analysis is necessary to evaluate functional joint stability.